Streptavidin magnetic beads exhibit highly specific reactions with biotinylated ligands such as proteins, antibodies, and nucleic acids, eliminating the need for activation, coupling, and blocking steps, and are easy to use. The streptavidin-modified magnetic beads have a particle size of 3 μm, high streptavidin loading capacity, and excellent hydrophilicity. They are superparamagnetic with good magnetic responsiveness and possess outstanding redispersibility and magnetic stability. The 3 μm beads have good uniformity and are suitable for applications such as single‑cell sequencing, liquid‑phase probe capture, nucleic acid pull‑down, and bacterial detection.
Product Information
| Parameter | Value |
|---|
| Concentration | 10 mg/mL | | Particle size | approx. 3 μm | | Surface potential | approx. –20 mV | | Streptavidin loading | 60–70 μg/mg beads | | Biotinylated BSA coupling capacity | 10–15 μg/mg beads | | Free biotin binding capacity | 800–1300 pmol/mg beads | | Storage conditions | Sealed, 4°C, do not freeze. Shake well before use. |
|
Scanning Electron Micrograph
Figure 1. SEM image of streptavidin magnetic beads (3 μm)
Instructions for Use
The following protocol uses biotinylated antibody as an example; it can be adjusted according to different experimental requirements.
The streptavidin magnetic beads (3 μm) have good hydrophilicity and monodispersity. They can be used directly after vortexing to mix.
Solvents and Materials Used
CB: 0.02 M carbonate buffer, pH 9.0
PBS: 0.02 M phosphate buffer containing 0.9% NaCl, pH 7.4
Washing buffer: 15 mM PBS pH 7.4, 0.1% Tween 20
Storage buffer: 15 mM PBS pH 7.4, 0.1% Tween 20 (containing a certain amount of glycine, casein, and preservative)
Procedure
1. Biotinylation of antibody
Dilute 100 μg of antibody with CB to 100 μL.
Quickly add 2 μL of 1 mg/mL PEGylated biotin (To be prepared by the customer) while vortexing.
Incubate at 37°C for 45 min.
Perform ultrafiltration centrifugation four times at 4000 × g for 10 min, then resuspend in PBS to 1 mg/mL.
2. Coupling of biotinylated antibody
Take 1 mL of streptavidin‑modified magnetic beads (10 mg/mL).
Add 20 μL of biotinylated antibody (recommended amount 20 μg) while vortexing.
Incubate at 37°C on a shaker for 1 h. Note: During shaking incubation, lay the tube horizontally to prevent bead sedimentation, which could affect coupling efficiency.
Perform magnetic separation and wash four times with washing buffer. Resuspend in storage buffer to the desired concentration.
Precautions
Before use, thoroughly mix the magnetic beads to avoid changes in bead concentration during aliquoting. Avoid prolonged sonication, which may damage the bead surface.
After taking the required amount of beads, perform magnetic separation and wash 2–3 times with pure water or the buffer solution to be used before proceeding with the experiment.
Avoid freeze‑thaw cycles during the use and storage of the magnetic beads.
